The present invention relates to a process for the purification of organic solutions of percarboxylic acids and more particularly of organic solutions of percarboxylic acids obtained by reaction of the corresponding carboxylic acids or carboxylic anhydrides with hydrogen peroxide in the presence of a catalyst such as sulphuric acid.
It is known to manufacture organic solutions of percarboxylic acids by reacting an aqueous solution of sulphuric acid and hydrogen peroxide with an organic solution of the corresponding carboxylic acid in a liquid-liquid extraction device and washing the resulting organic solution of the peracid by means of a very concentrated aqueous solution of sulphuric acid (French Patent Application No. 78/12,254, filed on Apr. 24, 1978 in the name of INTEROX CHEMICALS LTD). The object of this purification is to reduce the hydrogen peroxide content of the organic solution obtained. However, it has the disadvantage of producing an organic solution of the peracid which has a rather high sulphuric acid content, and this can encourage corrosion and side-reactions during the subsequent use of these organic solutions, for example for the epoxidation of olefins.
It is also known to manufacture solutions of percarboxylic acids in benzene by reacting a carboxylic acid with hydrogen peroxide in an aqueous phase in the presence of an acid catalyst, extracting the peracid from the resulting mixture by means of benzene and washing the resulting organic solution of the peracid with water or with sulphuric acid diluted to 25% (Belgian Pat. No. 808,108, filed on Nov. 30, 1973 in the name of DEGUSSA). This process has the disadvantage of giving an organic solution of the peracid in which the water content is too high, which again encourages corrosion and side-reactions during subsequent use of these organic solutions, for example for the epoxidation of olefins.